← The polytunnel
H11-04 · Module 4 of 7 · Pages: 19 · Worksheets: 6
Ventilation, irrigation and automation
How to keep temperature and humidity right in the polytunnel, how much water it needs and how to deliver it drip by drip, and what to automate with and without power
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In short
- Openings need at least 20 % of the floor area, ideally low on the sides and high at the ends.
- Target daytime temperature for warm crops is 20–28 °C (68–82 °F); above 32 °C (90 °F) tomato flowers don't set.
- Open in the morning, close in the afternoon. Humidity above 85–90 % for more than a few hours means disease.
- In summer a tunnel needs roughly 3–6 L of water per m² a day, best by drip, in the morning.
- Automation helps, but there must always be a manual way when the power goes off or a sensor fails.
What's inside
Chapters
- Climate in the tunnel: what you measure
- How many openings a tunnel needs
- Ventilating through the day and the year
- Cooling in summer
- Water: how much and when
- Drip irrigation in the tunnel
- Automation without power
- Automation with power
- When you are not at home
- Daily routine
- Most common mistakes
- Printable checklist
Worksheets
- Water calculator
- Vent calculator
- Drip system plan
- Climate log
- Climate and water calendar
- Shopping list for water and automation
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